There is a serious gap between required accuracy and current accuracy on nuclear data for developing innovative nuclear reactor systems. To bridge this gap, an international joint activity entitled Improving Nuclear Data Accuracy of Am and Np capture cross sections (INDA) has being performed under WPEC. In this joint study, the forefront knowledge of energy dependent cross section measurements, spectrum averaged experiments, relevant nuclear structure data, and evaluations are intended to be integrated on the capture cross sections of Am and Np. From the joint study, it was shown that integration of knowledge from the independent specialities enables us not only to crosscheck between data obtained by different techniques but also to improve the measurement accuracy of each other.